This invention relates to the treatment of gallstones and more particularly to a double balloon catheter and method of using a double balloon catheter for the treatment of gallstones.
In the past, gallstones have been treated with surgery, but this treatment is usually reserved for patients with gallstones producing symptoms. The operative techniques vary and may include cholecystectomy alone, or cholecystectomy combined with common duct exploration. Operative mortality rates vary with age and other comorbid conditions, and when elevated, make surgery an unattractive treatment.
In the last decade, treatment of gallstones by dissolution with orally administered bile acids such as chenodeoxycholic acid (CDCA) or ursodeoxycholic acid (UDCA) has been sucessfully accomplished. These agents work by inducing cholesterol unsaturation of bile. While dissolution of stones with orally administered bile acids eliminates many of the risks associated with surgery, many other problems are presented. First of all, complete dissolution occurs in only 30 to 40% of the patients (low index of efficacy). In addition, high doses of CDCA are required (15 mg/kg body wt/day resulting in doses of 1000 mg or more daily), and in order to achieve the dissolution, the duration of treatment must be rather long, i.e. on the order of 1 to 2 years. Furthermore, toxic side effects of the medications are encountered such as bile acid diarrhea, increase in serum cholesterol possibly leading to elevated cardiac risk, biochemical changes indicating liver abnormalities and changes in liver histology.
The infusion of monooctanoin (a dissolution agent) directly into the biliary tree by catheter has also been used to dissolve gallstones. Although this is a more direct method for dissolving gallstones than treatment with orally administered bile acids, monooctanoin is not a very effective solvent and dissolution times are on the order of days. This technique has therefore been reserved for large common duct stones which involve more extenuating clinical situations which eliminate other treatment options. Although bile exclusion and stirring are known to increase the effectiveness of monooctanoin, no device capable of excluding bile is currently used or available for treating gallstones with monooctanoin. Therefore, the monooctanoin is simply infused into the bile duct in the vicinity of the target gallstone with the patient's bile present.
Recently, methyl tertiary butyl ether (MTBE) has been shown to dissolve cholesterol gallstones much faster than either bile acids or monooctanoin. MTBE can dissolve gallstones about 50 times faster than monooctanoin in vitro. Furthermore, MTBE has, in fact, been instilled directly into the gallbladder by a catheter to successfully dissolve gallstones in humans. To do so, the catheter is placed into the gallbladder via a percutaneous transhepatic approach after a computed tomography scan of the liver with contrast enhancement demonstrates that the gallbladder has a sufficient area of attachment to the liver. In actual tests, the gallstones were successfully dissolved after seven hours of therapy in two patients, and another patent had only partial dissolution after 12 hours of treatment. The only ill effects suffered by these patients were mild pain and transient elevated white blood cell count (21,500) in one subject.
In view of the apparent advantages of using MTBE (or even monooctanoin) to dissolve gallstones, a need has developed to provide a means to deliver the MTBE to the gallbladder to dissolve the gallstones while at the same time excluding bile from the treatment area in a safe and effective manner. While catheters capable of delivering a dissolving agent to the gallbladder are currently known and available on the market, none of the known catheters are acceptable for this purpose since there are no known devices capable of excluding bile from the site of action of the dissolving agent or capable of directing or confining the dissolving agent to any particular site (e.g. the gallbaldder fundus).
An ERCP cannula, a single lumen plain catheter, is one such known catheter. It is generally constructed of clear plastic so one can visualize air bubbles. The tip of the catheter has graduated markings to gauge depth of insertion, and the catheters are approximately 200 centimeters in length with an outer diameter related to the size of the endoscope through which they are passed. No balloons are attached to these catheters and Luer locks are located on the proximal end so that after insertion through an endoscope they must be used with the endoscope in place. These catheters are used for diagnostic study of the common bile duct and the pancreatic duct by infusion of radiopaque dye through the catheter lumen.
Nasobiliary drain catheters are 200 to 300 centimeter long catheters (about 100 centimeters longer than ERCP catheters). The outer diameter is related to the size of the endoscope through which the catheter is passed, and the inner diameter must be large enough to allow passage over a guide wire. Nasobiliary drain catheters may have a pigtail distal end so the catheter will remain in place after the endoscope is removed. Often, such a catheter will include multiple holes at the distal end to facilitate infusion and drainage. These catheters are used for drainage of bile and infusion of medication into the common bile duct. Also, cholangiograms with dye may be done through a nasobiliary drain catheter. Unlike ERCP cannulae, the proximal end of these catheters have no Luer locks to allow the removal of the endoscope through which they were passed. There are no balloons at the distal end of these catheters for bile duct occlusion.
Another type of known catheter is the single balloon biliary occlusion catheter which is the same as an ERCP catheter except that a balloon is positioned at the distal end. These catheters are used for extraction of common bile duct stones and for the infusion of radiopaque dye into the biliary tree when an incompetent sphincter at the ampulla of Vater prevents retention of the dye. Thus, single balloon biliary occlusion catheters are used for diagnositic purposes. They have proximal Luer locks, and therefore they can only be used with an endoscope left in place.
None of the catheters described can be used for injecting a dissolving agent selectively into the gallbladder or a localized region of the common bile duct while at the same time being capable of excluding bile from the treatment area. In view of promising results obtained from the use of MTBE to dissolve gallstones the need for such a catheter has increased.
It is therefore a principal object of the present invention to provide a catheter for use in delivering and applying a dissolving agent to gallstones while at the same time preventing the passage of bile into the treatment area.
Another object of the present invention is to provide a catheter which will prevent or decrease loss of any dissolving agent either up into the biliary tree or down into common bile duct and pancreas or gastrointestinal tract via the Amulla of Vater.
An additional object of the present invention is to provide a catheter which is effective in treating gallstones lodged in either the gallbladder or the common bile duct.
A further object of the invention is to provide a catheter for infusing an agent around gallstones in the biliary tree.
A still further object of the present invention is to provide a catheter for use in the treatment of gallstones which is simple in construction and therefore cheaply manufactured.
Yet another object of the present invention is to provide a catheter for use in the treatment of gallstones which may be easily used in a safe manner without surgery or percutaneous needle aspiration of the gallbladder and their attendant complications.